The present invention relates generally to seals, and more particularly to multilayer, extruded seals having improved physical characteristics and reduced permeability to fuel vapors, and to a method for the manufacture of such seals as well as to the use of such seals in automotive fuel system components such as an air intake manifold.
In recent years there have been numerous restrictions and regulations imposed upon manufacturing industries in general and particularly upon automotive manufacturers, which are intended to reduce the amount of potentially harmful contaminates from being released into the environment by such industries. In the automotive industry, such regulations and restrictions severely limit the amount of hydrocarbon fuel vapor and other chemical materials that can permeate from of motor vehicles. Typically, the various seals employed in the automotive industry are used in grooves for maintaining the seal member in place. Typically, the seal members are molded and are composed of fluoroelastomer rubber materials. However, these molded fluoroelastomer seal members are expensive to manufacture due, in part, to the slow production cycling time and, in part, to the expensive tooling required for the manufacture of such molded seal members. For example, molded seal members typically have retention features located on both the inside and outside of the part for retaining the seal member in a seal groove. This works well, but creates more exacting tolerances in the width of the seal member as well as the height of the seal. Since it is the height of the seal, rather than the width, that is responsible for the sealing function, exact width tolerances are not critical in most sealing functions. Furthermore, such molded seals are prone to excess parting line flash which can lead to a separate operation to remove the parting flash from each individual seal. In some instances the parting flash may be severe enough to lead to total rejection of the seal members.
Accordingly, there is a need in the automotive industry for an improved fuel system seal which meets industry standards and a method for manufacturing automotive seals which overcomes the high costs and manufacturing problems associated with the manufacture of prior seal members.